Screwdrivers



P. A. SANDYS Oct. 13, 1959 SCREWDRIVERS Filed May 10, 1956 Invenfor PM? 0.. M

n ANJTI United States Patent SCREWDRIVERS Peter Anthony Sandys, London, England Application May 10, 1956, Serial No. 584,112 Claims priority, application Great Britain May 20, 1955 2 Claims. (Cl. 145-50) This invention relates to screwdrivers of the kind adapted to grip or hold a screw by engagement with the slot in the head thereof, such screwdrivers being particularly useful for inserting small screws generally and for inserting screws in relatively inaccessible places.

The object of the present invention is to provide an improved hand tool of this character which is positive in action and easy to manipulate.

According to the invention the improved screwdriver comprises a screw-engaging bit the tip portion of which is slotted longitudinally to receive the outer end of a resilient blade or strip, means being provided for flexing or distorting the blade in such manner as to urge the outer end thereof away from the bit and so cause the bit and the blade to grip friotionally the opposed side walls of a screw head slot.

In the preferred arrangement, the screw engaging bit is located partly within a tubular body or sleeve but projecting from the end thereof, the flexing or distortion of the blade to render it operative being eifected by relative axial movement of the bit and sleeve.

Reference will now be made to the accompanying drawings which illustrate several embodiments of the invention and wherein:

Fig. l is a side elevation of a first and preferred form of the invention,

Fig. 2 is an axial section through the tool shown in Fig. 1,

Fig. 3 is a fragmentary sectional view showing the bit of Fig. l in the operative position, and

Fig. 4 is a sectional view showing an alternative construction.

Referring first to Figs. 13, it will be seenthat the screw-engaging bit 1 is located within the outer end of a metal sleeve 2 the inner end of which is secured, as by spot welding to a shank member 3, said sleeve and shank being enclosed by an insulating covering 4 formed integrally with a moulded handle 5. The outer end of the bit 1 is tapered to form the usual straight-edged tip, the side faces of this bit portion being such that adjacent the tip they are parallel or even diverge slightly towards the tip edge to ensure that the bit engages firmly the opposed walls of a screw head slot into which it is inserted. Alternatively, the tip portion of the bit may be defined by two parallel side faces which at a distance inward from the extreme tip diverge to the full diameter of the tip. The bit is slotted longitudinally through its length as shown at 6 and disposed within the longitudinal slot is blade 7, said blade being so shaped as to provide a substantially straight outer end portion 7a aligned with the slotted tip of the bit, a curved intermediate portion 7b and an inturned inner end portion 7c which abuts the inner end face of the bit. The bit is also formed with a transverse slot 8 through which extends a cross pin 9 secured at its ends in the Wall of the sleeve 2, said pin being located between the inner wall of slot 8 and the resilient blade and, the ends ofsaid slot, serve to limit axial movement of the bit relative to the sleeve. A compression spring 10 disposed the sleeve 2 bears at one end against the fixed shank 3 and at the other end against a plunger 11 which exerts an outward thrust upon the bit.

It will be noted that the inner end portion 70 of the resilient blade extends at slightly less than a right angle to the blade portion 7 b and thus when the bit is in the free or projected, position shown in Figs. 1 and 2, the pressure of the plunger 11 upon the blade portion 70 tensions the blade slightly in a manner such as to cause the outer blade portion 7a to lie snugly the flush with the tip of the bit such that the tip can be readily entered in the slot of a screw head.

In use and assuming that a screw is to be inserted ina relatively inaccessible position, the tip of the bit is inserted in the screw slot and, by light pressure on the screw, the bit is forced back into the sleeve. During this movement the cross pin 9, riding along the slot 8, urges the outer blade portion 7a to lie snugly within and flush and thus the tips of the bit and the blade are caused to grip the screw by frictional engagement with the walls of the screw slot. The displacement of the cross pin relative to the resilient blade also presses the blade portion 7b into frictional engagement with the sleeve 2 whereby the bit is held in the retracted position and so retains the screw thereon while entering the screw in the workpiece to receive it. When the screw has been driven home, the screwdriver is withdrawn from the screw head whereon the blade portion 7a, under the inherent tension in the blade, springs outward to the position shown in broken lines in Fig. 3. This movement, however, relieves the blade of its frictional grip on the wall of the sleeve and, under the action of the spring 10, the bit is thereupon restored to its initial or projected position.

Fig. 4 illustrates a modification of the arrangement above described in which the bit 1a is integral with the shank 3a, an outer sleeve 2a being movable axially thereon and the relative movement of the bit and sleeve being operable to tension the blade as in the manner previously described. The sleeve is preferably hand operated, for which purpose it may be provided with a knurled finger ring or flange 12 on its inner end, although if desired spring means may be provided for uring the sleeve inwardly on the combined bit and shank.

In either of the forms above described, the blade shown may be substituted by a resilient blade which is kinked 0r stepped intermediate its ends to provide a pivot or fulcrum point bearing against the base of the slot 6 in the bit. The portion of the blade disposed inwardly of the fulcrum is bowed and in this region the enclosing sleeve provides an abutment which, upon relative axial movement of the sleeve and bit, flattens said bowed blade portion and so urges the tip of the blade away from the bit to secure the action previously described.

I claim:

1. A screwdriver comprising a sleeve, a screw-engaging bit having a sliding fit within the sleeve and slotted longitudinally over its tip portion, a resilient blade inclined to the axis of the sleeve and extending from a side of the sleeve toward an opposing wall of the bit and having an outer end portion located in the'slot in the bit, and a cross pin carried by the sleeve and engageable with the inclined portion of said blade, said pin being operable by relative axial movement of the sleeve and bit to distort the blade in a manner to urge the outer end thereof away from the tip of the bit to cause the bit and the blade to grip frictionally the opposed side walls of a screw head slot and to press the inner end portion of the blade into frictional engagement with the sleeve to pre- References Cited in the file of this patent vent relative axial movement between the bit and sleeve.

2. A screwdriver as defined in claim 1, including 21 UNITED STATES PATENTS spring plunger in said sleeve for urging the bit to a for- 1,359,384 James Nov. 16, 1920 Wardly projected position, and wherein said resilient blade 5 1,75 8,162 Lemieux May 13, 1930 has a. laterally inturned portion at its inner end which 2,013,826 Jacobson Sept. 10, 1935 is engaged by said spring plunger and is so located rela- 2,227,466 Runge Jan. 7, 1941 tively to the bit that when the bit i in said forwardly 2,313,710 Gemmell Mar. 9, 1943 projected position the blade is so constrained that its 2,506,922 Hansen May 9, 1950 outer end portion is urged by said spring plunger into 10 2,562,347 Young July 31, 1951 close relation with the tip of the bit. 2,657,724 Sheff Nov. 3, 1953 g 

